Well for myself, it's got to be dark colored if not just plain ole black. I don't get with the red stuff and the guys using the kitty litter stuff...I don't see how they stand that grey color. I guess maybe seeing it in person is different from thought or pictures but for myself I prefer black substrate. So whatever I do, it'll have to be capped with something black.
What about dual layer did you not like? I just figured that going with different layers would have to be better than just plain "rocks". I mean I know Eco isn't just rock, it has other things in it and all that but you should understand what I'm saying. I know aquatic plants differ from houseplants and yard plants...but you don't put them in rocky substrate and expect anything good from them.
I've had massive problems with not being able to grow plants. I had some issues that I think I've resolved. But in the meantime, I wanted to research and gather opinions on substrate just so I could be prepared if my changes didn't net any good results. Because at this point, I think I really should see some fair growth out of my plants and not see so much dying going on anymore. And if I don't, then the way I see it, it's got to be the substrate that is holding me back...or the plants rather.